The use of motor assemblies actuated by a spring has been known for at least approximately 100 years for window shades. Typically these assemblies utilized clutch mechanisms requiring free-floating balls or pawls or pivotally mounted pawls, often controlled by centrifugal force generated by rapid rotation of the shade roller. Alternatively, several devices utilized a slow movement to permit a latching action, whereas rapid movement of the roller retained an unlatched condition. These mechanisms typically required numerous components to be assembled to form the clutch or racheting arrangement between the rotating portion, normally fixed to the roller, and the non-rotating part.
For example, U.S. Pat. No. 256,736, issued to W. P. Putnam on Apr. 18, 1882, discloses the use of a spring motor mechanism having a pawl pivotally mounted on a collar on the spindle. A latching action was accomplished by a combination of centrifugal action and a lifting lug when the shade was wound or unwound rapidly. U.S. Pat. No. 301,771, issued to J. C. Sturgeon on July 8, 1894, similarly discloses the use of a spring motor mechanism, but has a pawl mounted on the spear and provides rachet type notches in the outer flange of the roller end-cap. Latching action was accomplished in the device by gravity acting upon the pawl to engage the rachet teeth.
U.S. Pat. No. 1,681,767, issued to J. Goodman et al., on Aug. 21, 1928, utilizes free-floating pawls with a notched stud or stationary member, to which the pawls hook upon slow rotation of the roller in one direction, but against which the pawls do not hook or latch upon rapid rotation in either direction or slow rotation in the opposite direction.
U.S. Pat. No. 3,115,927, issued to H. Znamirowski, on Dec. 31, 1963, discloses a pivoted pawl arrangement requiring the assembly of numerous small parts to obtain a pawl and ratchet mechanism which operates due to gravity and centrifugal force. U.S. Pat. Nos. 2,586,340; 3,763,916 and 4,009,745 are exemplary of patents utilizing balls in conjuction with recesses wherein the latching action is accomplished by the use of gravity and centrifugal force.
In all of the aforementioned patents, a multiplicity of parts were required which complicated the assembly of the motor and added to the cost of its manufacture. In addition, shades utilizing these devices were often inconsistent in operation and frequently could not be positioned at a desired level except with difficulty and repeated attempted latching operations.
Therefore, it is one object of the present invention to provide a motor and roller support and clutch mechanism of simplified construction, which is easily and inexpensively manufactured from only a few parts.
It is another object of this invention to provide a simplified clutch mechanism employing a housing and spindle having a pawl secured thereto, thus eliminating free-floating balls, pivoting pawls or other small parts as heretofore required.
Still another object of this invention is the provision of a simplified motor construction employing a unified spindle, pawl and bracket engaging element which eliminates difficulty assembled small parts, such as balls and free-floating or pivoted pawls.
These and other objects and advantages of the present invention will become apparent from the following description when the same is considered in conjuction with the accompanying drawings.